The 23-year-old has been caught up in a drugs scandal in the past, with a 16-month disqualification handed out by the International Swimming Federation in 2014 after she tested positive for anabolic steroid DHEA.

Given that this is her second failed test, the latest reports suggest that Efimova could well be handed a life ban from the sport, with the All-Russian Swimming Federation admitting the athlete had tested positive for meldonium.

Efimova won bronze in the 200m breaststroke at the London Olympics in 2012.

The notoriety of meldonium has also led to a host of US sports looking to outlaw the substance.

WADA's banned substances list is not automatically adopted by the governing bodies of American sports, with only Major League Soccer and the US Olympic Committee outlawing meldonium at the start of the year.

As such, other major sports such as baseball, basketball and ice hockey must work in collaboration with player unions if the drug is to be banned.

"We are still in discussions with the Major League Baseball Players Association regarding any additions to the banned list in the Major Leagues for the 2016 season," MLB spokesman Patrick Courtney said.

Officials from both the NBA and NFL have stated that the usage of meldonium will be discussed with relevant committees, with each sport’s list of banned substances to be reviewed.

NHL spokesman Schuyler Baehman said meldonium may well be added to the banned list but this would only happen before next season.